1. Technical Field
The present application relates generally to enhancing semiconductor wafer manufacturing and, more specifically, relates to positioning a semiconductor wafer with respect to the position of a support of a rotatable chuck to enhance wafer bevel edge bead removal (EBR) accuracy and reduce asymmetrical application of photo resist on a wafer during semiconductor wafer manufacturing.
2. Related Art
Photo resist layers are widely used in modern integrated circuit processing. A photo resist layer is applied to a semiconductor wafer by flowing a photo resist liquid onto a wafer while spinning the wafer.
FIG. 1 is a schematic diagram illustrating a photo resist spin coating process 100. A wafer has been positioned on a support of a rotatable chuck. Early in the spin coating process 100, photo resist is dispensed onto the wafer at action 101. Photo resist is spread over the wafer while the support (and the wafer resting on the support) begins to spin at action 103. At action 105, the support and wafer continue to spin as the layer of photo resist becomes thinner. At action 107, some photo resist solvent is evaporated during the spinning. At action 109, edge bead removal (EBR) and backside rinse processes begin.
FIG. 2 is a schematic diagram 200 illustrating a wafer 205 prior to undergoing edge bead removal (EBR) and backside rinse processes. The wafer 205 has a photo resist layer 203, and the spin coating process has resulted in edge beads 201 of photo resist at the edges of wafer 205. Further, backside contamination 207 has formed on the backside of the wafer 205. The edge beads 201 and backside contamination 207 are caused by air flow patterns 250 during the spin coating process.
FIG. 3A is a schematic diagram illustrating a conventional apparatus 300 for removing edge beads and backside contamination. A wafer 305 is positioned on a spin chuck 313 having a support 315. Edge bead removal (EBR) nozzle 311 and backside rinse nozzles 309 are positioned above and below the spin chuck support and are used to remove the edge beads and backside contamination.
FIG. 3B is a schematic diagram illustrating a close up view of edge bead removal (EBR) processes 350. An edge bead removal (EBR) nozzle 311 is used to remove a layer of photo resist 303 at the edge of a wafer 305. Process 350 shows that the edge bead removal (EBR) nozzle 311 is moved back and forth in a laterally or horizontally to remove a the photo resist 303 at the edge of the wafer 305. The positioning of the wafer 305 with respect to the edge bead removal (EBR) nozzle 311 often results in variations in edge bead removal (EBR) cut widths at the edges of the wafer 305.
Recent manufacturing processes require a high level of precision of the wafer edge cut, and the wafer edge profile is becoming more important both at the immersion lithography stages of wafer manufacturing and during pre-layer profiling. Thus, it is desirable to find new approaches for improving the accuracy and precision of various wafer edge cuts and wafer profiling at a variety of stages of wafer manufacturing.